A numerical study on an earth dam safety by using finite element method

Re - assessment of earth dam's safety from geotechnical point of view is very important issue, because if failure occurs in the dam the losses will be enormous. In the last century the worl d faced many disasters because of failure of dams. Yet, According to the statistics, in the last two decades there was annually one or more dam failure occurred in worldwide because of faults in design or construction or maintenance. Dam failure is a disas ter and makes a huge hazards, it causes damages in everything in the receptor area in downstream. Usually there are huge losses in people, properties and environment. Therefore a careful attention and re - assessment should be focused on earth dams to preven t possibility of failure ,b ecause earth dam effected widely by many internal and external factors and that the earth dams are becoming widespread because of its competitive advantages over other types of dam where it is: low cost, easy to construct, it can be constructing in difficult site condition , etc. Failure of earth dams may occur for many reasons: creating of piping phenomenon and erosion may grow inside or beneath the dam due to seep age of water, also earthquake may causes dam failure, side slopes of the dam may slide during or at : the end of the construction , full reservoir level or in case of rapid drawdown of reservoir level, or dam failure may be due to other factors. In this thesis geotechnical re - assessment conducted for Shauger earth dam as a case study. Where, slope stability examined for many conditions: at the end of construction, steady state seepage, rapid drawdown, instantaneous and slow drawdown of the reservoir level . While seepage investigated for both static steady state and transient, also piping investigated. Moreover dam examined for earthquake case by using dynamic analysis to check the effect of this case on the dam stability, deformation and seepage. The dam simulated in numerically model and analysed by using finite element method. Geostudio 20 12 , software used to perform the analysis. Results show that Shauger earth dam is not in the safe case according to the Ordinary and Janbo methods for U/S slope stabi lity analysis, for the case of rapid drawdown and is not in the safe case according to QUAKE/W Stress method for the D/S slope stability, for the case of full reservoir (maximum water level) with earthquake. Therefore, there is a risk from geotechnical poi nt of view. Key Words: Earth dams, Embankments, Dam assessment, Dam's safety, Geostudio, Slope stability